Articles of footwear having lines of flexion

ABSTRACT

The invention herein is directed toward footwear containing a central flex zone comprised of a novel combination of a central flex channel with a central flex element that imparts either bidirectional or multi-directional flexion to the shoe, according to various embodiments, thereby allowing more natural flexibility and allowing all surface contacting members to independently engage and disengage from the contact surface of the user as the wearer&#39;s weight shifts. The flex zones also naturally adapt to the amount of stress put on the sole from ground elements, such as rocks or branches that the sole encounters during wear and to adjust to different terrain due thereby being particularly useful in applications such as construction boots and athletic footwear.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The present invention was not developed with the use of any FederalFunds, but was developed independently by the listed inventor.

BACKGROUND

1. Field

The present invention relates to the field of footwear. Moreparticularly, the invention is directed to a new shoe sole constructionwherein the shoe includes a midsole welted between an upper structureand the bottom outsole and wherein the outsole comprises an extrudedchannel spanning preferably centrally from forefoot to heel area andcomprising a shock absorbing cushion that extends and protrudes throughthe channel within the outsole.

2. Background

Industry reports indicate that as of 2010, the apparel footwear andaccessory industry had a market capitalization of approximatelyfifty-seven billion US dollars. The shoe market evolves continuously tomeet the varied needs of the consumers. Conventional articles offootwear traditionally include two primary elements, an upper structureand a sole structure. The upper structure provides a covering for thefoot that securely receives and positions the foot with respect to thesole structure. The sole structure is secured to a lower surface of theupper structure and is generally positioned between the foot and theground in order to cushion and protect the foot while walking. The solestructure may in addition provide traction and control of foot motion.

The upper structure (the “upper”) forms a void on the interior of thefootwear for receiving the foot. The void has the general shape of thefoot, and access to the void is provided by an ankle opening.Accordingly, the upper extends over the instep and toe areas of thefoot, along the medial and lateral sides of the foot, and around theheel area of the foot. A lacing system may be incorporated into theupper to selectively increase the size of the ankle opening and permitthe wearer to modify certain dimensions of the upper, particularlygirth, to accommodate feet with varying proportions. In addition, theupper may include a tongue that extends under the lacing system toenhance the comfort of the footwear, and the upper may include a heelcounter to limit movement of the heel.

The sole structure (the “sole”) is designed to address the particularfunctionality and use of a shoe. It became one of the objects of thefootwear industry to create a sole structure to reduce and controlground reaction forces to the wearer. Lug soles were created as a typeof outer sole found on heavy-duty and utility shoes such as hiking bootsor work boots. Lug soles are typically thick and designed with deepindentations to improve stability and traction. The pattern of lug solesvaries to include indentations such as V-shaped and diamond shapedindentations. Lug soles are most frequently found on construction,fishing, hunting, logging, hiking, and other utility boots. Lug solesare typically made of rubber and some may be injected molded fromthermoplastic polymers such as polyvinyl chloride (PVC) or polyurethane(PU). Lug soles are generally slightly wider than the perimeter of theshoe. Though lug soles offer improved traction and stability, they arelimited in flexibility and control. Lug soles also have a tendency toaccumulate mud in the deep indentations and they can be messy anddifficult to clean.

Athletic shoes are a generic name for footwear that is primarilydesigned for sports or other forms of physical exercise and have come tobe used for casual everyday activities. They are also known as sneakers,sneaks, sports shoes, trainers, cross-trainers, jogging shoes, daps, gymshoes, running shoes, runners, tennis shoes, rubber shoes, canvers andother names commonly adapted to particular localities. Attributes of anathletic shoe include a flexible sole with appropriate tread for thefunction ability to absorb impact. As the industry and design haveexpanded, the term “athletic shoes” is based as much on the design ofthe bottom or sole of the shoe as the aesthetics of the top or upper ofthe shoe. Today's designs include sandal, elevated, and Mary Jane stylessuitable for running, dancing and jumping. The shoes themselves are madeof flexible compounds, typically featuring a sole made of dense rubber.While the original design was basic, manufacturers have since tailoredathletic shoes for the differing purposes for which the shoe can beused. A specific example of a particular design is the spiked shoedeveloped for track running. Hiking, climbing and mountaineering shoeshave become a niche in the athletic shoe industry. Such shoes combineelements of traditional athletic shoes together with elements requiringa more rugged traction and stability.

In addition to functionality, shoes are also designed in differentshapes suited to different foot types and gait. Generally, such shoes,especially running shoes, are divided into neutral, over-pronation andunder-pronation (supination) shoes to fit the respective foot strike ofthe wearer. As athletic shoes become more advanced, amateur joggers, aswell as marathon runners, are beginning to purchase shoes based on theirrunning or walking style and foot arch. This is often important forinjury prevention, as well as to increase athletic efficiency andcomfort.

A common form of footwear construction, referred to as weltconstruction, incorporates a “welt”, which is a strip of leather,rubber, or plastic that is stitched to the upper and the insole of ashoe as an attach-point for the sole. The space enclosed by the welt isthen filled with cork or some other filler material (often either porousor perforated, for breathability), and the outsole is both cemented andstitched to the welt. Shoes with other types of construction may alsohave welts for finished appearance, but they generally serve little orno structural purpose.

Other sole designs have been introduced in order to reduce the weltwhile rendering flexibility to the wearer. For example, U.S. Pat. No.6,163,982 discloses a the structure of a conventional shoe sole that hasbeen modified by having its sides bent up so that their inner surfaceconforms to a shape nearly identical but slightly smaller than the shapeof the outer surface of the sides of the foot sole of the wearer,instead of the shoe sole sides conforming to the ground by parallelingit, as is conventional. The shoe sole sides are sufficiently flexible tobend out easily when the shoes are put on the wearer's feet andtherefore the shoe soles gently hold the sides of the wearer's foot solewhen worn, providing the equivalent of custom fit in a mass-producedshoe sole.

In subsequent construction of footwear, a midsole was introduced that ispositioned between the upper and the sole of the shoe in order to rendergreater comfort to the wearer along with other desirable advantages. Forexample, U.S. Pat. No. 6,763,609 to Robert Su disclosed a midsole thatpermits molten outer sole material to flow through the midsole duringthe molding process and fill the space between the insole and themidsole and thus sandwich the midsole. This technique forms outer solesto be durably and flexibly attached to the upper structure without useof traditional adhesives. The term “outsole” was coined to differentiatethe midsole structure from the bottom-most sole structure that comesinto contact with the ground.

Numerous designs of footwear have been created that attempt toincorporate a variety of elements into the design and functionality ofthe shoe to improve flexibility and comfort. U.S. Pat. No. 6,854,198 toJeffrey Brooks discloses a design having medial, lateral and archregions that is based on the shape of the toes of the foot in attemptingto mimic a foot's natural outline and mobility. U.S. Pat. No. 5,012,597to Robert Thomasson discloses an athletic shoe sole with a twist flexregion positioned below the ball portion of the foot that attempts toconstruct a flex function which allows the wearer to twist the foot forathletic activities. U.S. Pat. No. 7,124,519 to James Issler discloses ashoe sole having a plurality of adjacent sections made of differentmaterials in order to improve flexibility. U.S. patent application Ser.No. 11/338,601 of Hazenberg et. al. discloses a shoe having a number offluid-filled chambers in one or more flexion zones of the sole. U.S.Pat. No. 7,650,707 to Campbell et. al. discloses an outsole with flexlines that improve the flexibility functionality of the shoe. U.S. Pat.No. 7,350,320 to Chandler et. al. discloses a shoe with a centralflexing point that is focused on a suspension system which allows theheel portion to act as a shock absorber cushioning element. Conversely,U.S. Pat. No. 7,707,748 also to Derek Campbell discloses a shoe with adesign that enables the flexing of the forefoot portion of the footwhile inhibiting heel movement for improved twisting or swinging actionin golf shoes.

The previous examples demonstrate the great focus that has been placedin the shoe industry on either the flexibility of the footwear or thedurability of the footwear in its construction. Despite the tremendoussize of the shoe industry, it continues to be desirable to create a shoestructure wherein the upper, midsole and the outsole structure operatecooperatively to provide comfortable footwear that is suited for a widevariety of ambulatory activities, such as walking, running, and jumping,as well as being rigid enough for other activities such as hiking,mountaineering and/or utility work among others and wherein the shoe isparticularly suited to the specific gait and pressure points of eachperson. The present invention addresses a number of issues in the shoeindustry. The invention features a novel structural configuration of theupper, midsole and outsole structures that allow greater mobility to thefoot of the wearer based on the particular movement of the foot of eachindividual while at the same time allowing traction, control andrigidity for more rugged functionality and use as discussed in greaterdetail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary and the following detailed description of theinvention will be better understood when read in conjunction with theappended drawings. For the purpose of illustrating the invention, thereare shown in the drawings embodiments which are presently preferred. Itshould be understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown.

FIG. 1 is an illustration of an article of footwear of the invention.

FIG. 2 is a bottom view of the outsole of an article of footwear of theinvention.

FIG. 3 is side view of the sole elements of an article of footwear ofthe invention.

FIG. 4 is a rear view of the sole of an article of footwear of theinvention and a rear view of the sole showing the lateral directionalflexion of the sole.

FIG. 5 is an alternative illustration of the sole of an article offootwear of the invention.

DETAILED DESCRIPTION

The following detailed description of the invention is made in referenceto the accompanying drawings, which form a part hereof, and which showby way of illustration various example structures of the invention. Itis to be understood that other specific arrangements of parts, examplestructures, and embodiments may be utilized and structural andfunctional modifications may be made without departing from the scope ofthe present invention. Also, while certain terms may be used in thisspecification to describe various example features and elements ofstructures the invention, for example, “heel”, “forefoot”, “midfoot”,these terms are used herein as a matter of convenience, e.g., based onthe example orientations shown in the figures and/or a typicalorientation during use. The terms “zones” and “regions” are usedinterchangeably herein. The term downward-facing surface refers to asurface area that is directed and oriented toward the ground.

“Footwear” is used interchangeably herein with “shoe” and means any typeof product worn on the feet, and this term includes, but is not limitedto all types of shoes, boots, sneakers, sandals, flip-flops, mules,scuffs, slippers, sport-specific shoes (such as golf shoes, tennisshoes, baseball cleats, soccer or football cleats, ski boots, etc.), andthe like. Footwear may protect the feet from the environment such asrocks and the weather, and/or enhance a wearer's performance, whetherphysically, physiologically, medically, or otherwise.

Footwear (10) is depicted in FIG. 1 and includes an upper element (20)and a sole structure (30). Upper (20) is formed from various materialelements that are stitched or adhesively bonded together to form aninterior void that comfortably receives a foot and secures the positionof the foot relative to sole structure (30). Sole structure (30) issecured to the downward-facing surface or lower portion of upper (20)and provides a durable, wear-resistant component for attenuating groundreaction forces as footwear (10) impacts the ground.

For purposes of reference, footwear (10) is divided into two generalregions: the exterior lateral zone (80) and an interior or medial region(90), as defined in FIG. 2. Further depicted on FIG. 2, footwear (10)comprises a toe or forefoot region (12), a midfoot region (14) and aheel or rearfoot region (16). Aforesaid regions (80), (90), (12), (14)and (16) are not intended to demarcate precise areas of footwear, butrather are intended to represent general areas of footwear (10) thatprovide a frame of reference during the following discussion.

Various materials may be utilized in manufacturing the upper element(20). Flexibility, durability and/or temperature regulation of the upperelement of a shoe may be regulated by incorporating multiple materiallayers that include an exterior layer, a middle layer, and an interiorlayer. A variety of materials are suitable for the upper, including thematerials that are conventionally utilized in footwear uppers.Accordingly, the upper may be formed from combinations of leather,synthetic leather, natural or synthetic textiles, polymer sheets,polymer foams, mesh textiles, felts, non-woven polymers, or rubbermaterials, for example. Portions of the upper can form coextensivelayers of material that are stitched or adhesively bonded together.Various layers within the upper element may be joined with adhesives,and stitching may be utilized to join elements within a single layer orto reinforce specific areas of the upper element.

In athletic footwear, materials forming the exterior layer of the upperelement may be selected based upon the properties of wear-resistance,flexibility, and air-permeability, for example. The exterior layer ofthe upper may be formed, therefore, from numerous material elements thateach imparts different properties to specific areas of the upper. Forexample, certain embodiments directed more toward athletic use may havean upper element having a configuration that provides ventilation,thereby cooling the foot and removing perspiration. In footwear intendedfor rugged activities such as construction or trekking, materials suchas leather or canvas elements may be added to the design of the upper.Further, the toe area and the heel area of the shoe may be formed ofmaterials such as leather, synthetic leather, or a rubber material toimpart a relatively high degree of wear-resistance. Leather, syntheticleather, and rubber materials may not exhibit the desired degree offlexibility and air-permeability. Accordingly, areas of the exterior ofthe upper may be formed from synthetic textiles imparting suchcharacteristics if desired in the particular design.

The mechanism for adjusting the fit of upper (20) and accommodatingvarious foot dimensions can be accomplished either by incorporation of atongue, with separate lacing or by other mechanisms known in the art.

In some embodiments of the invention, the portion of upper (20) in theheel region (12) may incorporate a conventional heel counter formed of asemi-rigid polymer material, for example, to ensure that the heelremains properly positioned with respect to the upper. The heel countermay be located on an exterior of the upper or within the variousmaterial elements forming the upper. However, the configuration of theupper and the sole structure (30) does not necessitate the presence of aheel counter. The shoe of the invention may include additionalstructures or elements, including conventional structures and/orelements known and used in the art, such as securing systems (e.g.,laces, buckles, hook-and-loop fasteners, zippers, etc.); heel counters;insole members; interior booties; sock liners; additionalimpact-attenuating elements; impact-attenuating foam columns; gas-filledbladders, and various others.

The sole structure (30) of the footwear of the invention comprises alayered configuration demonstrated by FIG. 3 that includes an insole(40), a midsole (50), and a shock absorbing cushion structure (60) thatis integrally connected to a surface-contacting outsole (70) thattogether provide both flexibility and abrasion-resistance and traction.

The insole of the invention (40) is a structure that is conventionally athin, comfort-enhancing member located within the upper and adjacent theplantar (lower) surface of the foot usually added to footwear in orderto enhance footwear comfort. Often the insole is formed of amoisture-wicking textile that removes perspiration from the areaimmediately supporting the bottom of the foot.

A middle layer of the sole of the footwear of the invention, the midsole(50) structure is generally integrally connected to insole (40)illustrated in FIG. 3. A conventional footwear midsole is a unitary,polymer foam structure that extends throughout the length of the footand may have stiffness or inflexibility that inhibits the natural motionof the foot. The midsole herein has a conventional articulated structurethat imparts relatively high flexibility and articulation. The flexiblestructure of the midsole (in combination with the structure of upper 20)is configured to complement the natural motion of the foot duringvarious activities.

Midsole (50) includes an upper midsole surface (52) and an oppositebottom midsole surface (54). Upper surface (52) is positioned adjacentto the upper (20) and may be secured directly to it, thereby providingsupport for the foot. Upper midsole surface (52) may, therefore, becontoured to conform to the natural, anatomical shape of the foot.Accordingly, the area of upper midsole surface (52) that is positionedin the heel region (12) may have a greater elevation than the area ofupper midsole surface (52) in the forefoot region (14). In addition, themidsole may form an arch support area in midfoot region (16), andperipheral areas of the midsole may be generally raised to provide adepression for receiving and seating the foot. In other embodiments, themidsole may have a non-contoured configuration.

Midsole (50) may be formed from resilient materials such as alightweight polymer foam material that helps to absorb ground reactionforces and protects the foot from objects that may contact the upperelement while simultaneously supporting the outsole. Stability devicescan be incorporated into the polymer foam material of the midsole tocontrol the degree of rotational movement of the foot. Examples ofstability devices are found in U.S. Pat. No. 4,255,877 to Bowerman; U.S.Pat. No. 4,287,675 to Norton et al; U.S. Pat. No. 4,288,929 to Norton etal; U.S. Pat. No. 4,354,318 to Frederick et al.; U.S. Pat. No. 4,364,188to Turner et al; U.S. Pat. No. 4,364,189 to Bates; and U.S. Pat. No.5,247,742 to Kilgore et al. In addition to stability devices,conventional midsoles may include fluid-filled bladders, as disclosed inU.S. Pat. Nos. 4,183,156 and 4,219,945 to Rudy, for example.

The Shock Absorbing Cushion

The footwear of the invention comprises a shock absorbing cushionelement (60) that according to the invention functions together withoutsole (70) in a novel configuration and design in order to rendersuperior foot motion control while rendering shock absorption,durability and traction. The shock absorbing cushion (60) is recessedbetween the midsole (50) and the outsole (70). As illustrated in FIG. 2and FIG. 4, in the preferred embodiment of the invention, the shockabsorbing cushion element (60) comprises one central protruding flexzone segment, the central flex element (62) that extends longitudinallyfrom the forefoot portion or toes (14) (e.g., at or near the toe area ofthe sole (30)) to the rearfoot portion or heel (12) (e.g., at or nearthe rear heel area of the sole (30)). Central flex element (62) isintegrally recessed within the central flex channel (72) forming twohalves or regions of outsole structure (70).

Midsole (50) and the shock absorbing cushion of the invention (60) arepreferably joined through a mechanical interface rather than an adhesiveor chemical interface. The primary element of a conventional midsole isa resilient, polymer foam material, such as polyurethane orethylvinylacetate, which extends throughout the length of the footwear.The properties of the polymer foam material in the midsole are primarilydependent upon factors that include the dimensional configuration of themidsole and the specific characteristics of the material selected forthe polymer foam, including the density of the polymer foam material.Similarly, suitable polymer foam materials for the shock absorbingcushion element (60) of the invention include ethylvinylacetate (“EVA”)or polyurethane (“PU”) that compress resiliently under an applied loadto attenuate contact surface reaction forces. Conventional polymer foammaterials are resiliently compressible, in part, due to the inclusion ofa plurality of open or closed cells that define an inner volumesubstantially displaced by gas. By varying these factors throughout themidsole, the relative stiffness, degree of ground reaction forceattenuation, and energy absorption properties may be altered to meet thespecific demands of the activity for which the footwear is intended tobe used.

Depending on a desired design aesthetic, the shock absorbing cushion(60) of the invention may be either open and exposed to the externalenvironment, such that it is distinctly visible and identifiable fromthe side view of the shoe; or it may be hidden within another material(such as in impact-attenuating material) or partially hidden in such amaterial, without departing from this invention. The thicknesses of themidsole and of the shock absorbing cushion are depicted graphically inFIG. 3 as thickness dimension (55) and (65), respectively.

The Outsole

The outsole of a shoe is generally the sole layer that is in directcontact with the ground. The outsole (70) of the invention is secured toa lower surface of the shock absorbing cushion (72) to providewear-resistance. As in conventional outsoles, the outsole of theinvention (70) is fashioned from a durable, wear-resistant material.Suitable materials for outsole (70) include abrasion-resistant materialssuch as any of the conventional rubber materials that are utilized infootwear outsoles, such as carbon black rubber compound, blown rubber,or a combination of blown and carbon rubbers.

The outsole (70) sometimes includes texturing in order to improvetraction of the footwear, illustrated in FIG. 5. Likewise, the outsole(70) of the invention forms the ground-contacting element of thefootwear of the invention. In the preferred embodiment of the invention,the outsole (70) is divided longitudinally into two regions or halvesextending from the forefoot (12) to the heel (16). As illustrated inFIGS. 2 and 5, the region of the shoe closest to the exterior of thefoot shall be termed the lateral region (80) and the region of the shoecloser to the interior of the foot shall be termed the medial region(90). The line or area of division between the two halves or regions ofthe outsole (70) forms the central flex channel (72) of the inventionthrough which protrudes the central flex element (62) of the inventionand extends from the forefoot (12) to the heel (16) and illustrated inFIGS. 2 and 5 or as will be discussed hereinbelow.

The thickness of the outsole is defined as the dimension that extendsbetween the shock absorbing cushion (60) and the outer bottom surface ofthe outsole (70) that is in contact with the ground. The thickness ofthe outsole may vary along the longitudinal length of the midsole. Thethickness is depicted graphically in FIG. 3 as thickness dimension (75).One skilled in the relevant art will recognize that a variety ofthickness dimensions and variations will be suitable for the outsoledepending on the use for which the footwear is contemplated anddesigned.

The Central Flex Zone

The shock absorbing cushion element of the invention (60) is designedsuch that it protrudes between the two longitudinal regions of theoutsole, the lateral region (80) and the medial region (90) through thecentral flex channel (72) thereby creating the central flex element(62). The central flex element is visible from the bottom view of theshoe as illustrated in FIG. 5. Together, the central flex channel (72)and the central flex element (62) form the central flex zone whichprovides a line of flex in the sole (30) and divide outsole (60) intothe lateral region (80) and the medial region (90). The central flexzone acts as the center flexing point for the sole. Whereas theconventional footwear outsole is usually a unitary element of polymerfoam, the central flex channel (72) of the invention forms a flexionline in the outsole and, therefore, imparts a direction of longitudinalflex in the sole. The manner in which the sole structure (30) isconsequently able to flex or articulate as a result of the novel centralflex zone disclosed herein, is graphically depicted in FIG. 4. Thecentral flex zone acts as a live hinge for the sole allowing the sole tomove in a birdlike flapping motion of its wings.

In general, during the time that the foot is in contact with the ground,the motion of the foot during walking is such that the foot typicallyrolls from the outside or lateral side to the inside or medial side, aprocess called pronation. That is, normally, the outside of the heelstrikes first and the toes on the inside of the foot leave the groundlast. The separation of footwear (10) into the lateral (80) and medial(90) regions creates a structure that allows the lateral and medialzones to move independently of each other allowing each of the regionsof the outsole to bend in response to elements on the ground and therebyimparting bidirectional flexibility and flexion.

The welt has always given boots its tough and durable trait. However thewelt takes away from a boots overall flexibility and ultimately adds tothe overall weight of the boot. Cement construction in is widely used bythe athletics footwear market for its flexibility and light weight. Theproblem with cement construction is that it does not impart toughnessand durability. In order to address the limitations presented by thewelt, the outsole of the invention utilizes the strength and durabilityfound in the welt. Thereby, in contrast to conventional footwear of theprior art, footwear of the invention directed to applications such asconstruction boots and trekking boots can handle the toughness anddurability required on the construction site and yet imparts a morenatural flexibility and comfort to the footwear. The central flex zonesallow the shoe to feel more like an extension of the foot, flexing inplaces at which the foot naturally wants to flex rather than fightingthe foot's natural motion which is the problem with common constructionand trekking boots. Further, the footwear of the invention is able toadjust to different terrain due to its ability to flex.

In one preferred embodiment of the invention, the weight of the welt iscountered by using a polyurethane injection molded midsole. This designeliminates the weight that is traditionally tacked on by the standardsolid rubber lug outsole. Adding the strength of the good year weltconstruction to the design combines the best qualities of athletic andoccupational footwear.

In the preferred embodiment, the lateral and medial regions form twoseparate segments on the outsole of the footwear of the invention.However, in yet another embodiment of the invention, lateral region (80)and medial region (90) are connected at the heel (16) of the footwearthereby forming one continuous segment. In another embodiment, lateralregion (80) and medial region (90) are connected at the forefoot segment(12) of the footwear thereby also forming one continuous segment. Alsocontemplated is an embodiment where the lateral and medial regions areconnected at both the heel (16) and toe (12) regions.

Though preferably the individual central flex channel (72) and thecorresponding central flex element (62) creating the line of flex extendcompletely from the forefoot (12) to the rearfoot (16) regions,embodiments are contemplated where the central flex element (72) extendsand protrudes only partially through the central flex channel (72) i.e.,the length of the central flex element (62) being less than the lengthof the central flex channel (72) along the outsole of the shoe.

Optionally, central flex element (62) comprises a longitudinal centralflex groove which imparts yet additional longitudinal bidirectionalflexibility and flexion. The flexible footwear of the types describedabove allow independent movement of the lateral and/or medial segmentsof the outsole member (e.g., independent movement or rotation withrespect to one another about the lines of flex) to thereby allow more ofthe outsole to remain in contact with the ground e.g., as compared tosupport structures that do not include such flexibility andindependently and relatively movable regions, which may improve safetyand functionality during operation on a construction worksite andadvantages during certain sporting activities such as for example duringa golf or baseball swing (or other swinging activities) as weight tendsto shift, and the wearer's center of gravity moves from the center ormedial side to the lateral side and/or moves from the lateral side tothe medial side. Moreover, the increased lateral stability and/ordecreased lateral flexibility as compared to the medial side's stabilityand/or flexibility characteristics provide excellent support and/orcomfort during various moving, twisting or swinging actions.

According to some embodiments of the invention, central flex element(62) (and central flex channel (72)) is positioned not precisely withinor toward the longitudinal center of the foot but either more laterallytoward the lateral region (80) or more medially toward the medial region(90), respectively. A configuration wherein central flex zone (62) ispositioned medially provides a shoe where the lateral side of the footis made less flexible and/or more stable than its medial side. Such adesign may be particularly useful for individuals having specific gaitcharacteristics, for example those individuals who tend to place moreweight toward the lateral part of the foot as they walk.

Embodiments of the invention are provided wherein the thickness of theoutsole (70) differs throughout the length of the shoe particularlywhere the thickness of the lateral region (80) differs from thethickness of the medial region (90). The variation in the thicknessesbetween the lateral and medial regions of the outsole with respect toone another allow for yet further control and comfort to the wearer,such as, for example, for individuals having specific preferences ormedical requirements for the height of their foot arches.

The central flex channel (72) may extend for any desired length in theoutsole without departing from the invention. The channel may run alongthe entire length of the shoe or along only a partial length of theshoe. The width of the central flex channel is from about 2 to about 20mm wide, illustrated as dimension (75) in FIG. 4, preferably from 4 mmto about 14 mm wide. Though preferred, not all of the central flexchannel (72) and the corresponding central flex element (62) in a givenshoe need have the same dimensional characteristics. The inventionherein will be operable as long as the dimensions of the central flexchannel (72) are greater than the dimensions of the central flex element(62) such that the central flex element (62) is able to protrude throughthe central flex channel (72). However, in the preferred embodiment, thedimensions of the central flex channel and the central flex element areapproximately equal so as to prevent rocks, soil or other groundmaterials to accumulate in the central flex channel which may causediscomfort to the wearer and potential puncture of the sole structure atthe recessed central flex channel.

The thickness of the central flex element (62) is preferablyapproximately equal to or less than the thickness of the outsole of theshoe. The thickness of the central flex zone may vary along itslongitudinal length. The thickness is depicted graphically in FIG. 4 asthickness dimension (63). For example, dimension (63) in the forefootregion (12), may be, for example, approximately 4 mm to 15 mm. Oneskilled in the relevant art will recognize, however, that a variety ofthickness dimensions and variations will be suitable for the centralflex element.

The width of the central flex element (62) of the invention is definedby dimension (65) demonstrated in FIG. 4 and is preferably typicallyapproximately equal to the width of the central flex channel (72) inorder for the central flex element (62) to protrude through the centralflex channel (72). The width of the central flex element is preferablybetween 2 mm and 20 mm, more preferably between 4 mm and 15 mm, and morepreferably between 6 mm and 10 mm. A relatively thin thickness of thecentral flex element will, in general, possess more flexibility thanflex element having a greater thickness. Variations in the thicknessmay, therefore, be utilized to modify the flexibility of the solestructure in specific areas of the foot. For example, the forefootregion may be configured to have relatively high flexibility by forminga central flex element with a lesser thickness while a relatively lowflexibility may be imparted to the midfoot region by forming the centralflex element with a greater thickness. Similarly, an intermediateflexibility may be imparted to the heel region by forming a central flexelement with a thickness that is between the thicknesses of the forefootregion and the midfoot region.

In other embodiments of the invention, multiple central flex elementsmay be introduced dividing the outsole of the shoe into various regions,for example, further separating and subdividing each of the lateralregion (80) and the medial region (90). In an example structure,provided is a shoe comprising three central flex elements, asillustrated in FIG. 5, having subdivided forefoot sub-lateral zones (82)and (84) and sub-medial zones (92) and (94), wherein each of the zonesprovide discrete areas of the sole structure such that they are eachindividually movable about the lines of flex (64) and (66) with respectto one another to allow the various regions to independently engage anddisengage from a contact with the ground elements. The dimensions of thecentral flex channel (72) and corresponding central flex element (62)may vary along the overall length, width, and/or depth of an individualzone segment.

While referred to as extending in the “longitudinal direction”, thecentral flex zone need not extend exclusively in a direction of alongitudinal center line of the sole structure. Rather, as shown in FIG.2, the term “longitudinal direction”, as used herein in this context,means that the central flex channel (72) and the corresponding centralflex element (62) creating the line of flex defined thereby extendpredominantly in the longitudinal direction, e.g., generally from theshoe's front or toe (12) toward its back or heel (16), and mayoptionally extend in a curved manner in order to, for example, tocorrespond to the location(s) of a typical foot's lines of flex and/orflexibility in the longitudinal direction or simply for a desirablefashion element. When such multiple longitudinally extending centralflex elements are present, the various segments need not be parallel toone another and they need not extend in precisely the same directions,in the same arch or curvature, or at the same dimensions (e.g., to thesame depth in the base level, at the same width or length, etc.)

Similarly, while referred to as extending in the “lateral direction”,the central flex channel (72) and the corresponding central flex element(62) creating the line of flex need not extend exclusively in adirection laterally across the sole structure. Rather, as shown in thefigures, the term “lateral direction”, as used herein in this context,means that the central flex channel (72) and the corresponding centralflex element (62) creating the line of flex defined thereby extendpredominantly in the lateral direction (e.g., generally from the shoe'slateral side toward its medial side), optionally in a curved manner(e.g., to correspond to a typical foot's lines of flex and/orflexibility in the lateral direction), as illustrated in FIGS. 2 and 5.Additionally, if desired, it is not necessary for an individual centralflex channel (72) and the corresponding central flex element (62) toextend completely across the sole. They may extend any desireddistances. When multiple laterally extending central flex channels arepresent (e.g., additional central flex channels in the heel and forefootportions, etc.), the various central flex channels need not be parallelto one another and they need not extend in precisely the samedirections, in the same curvature, or at the same dimensions (e.g., tothe same depth in the base level, at the same width or length, etc.).Optionally, if desired, the central flex elements and lines of flex inthe outsole structure may correspond to typical areas of flex or jointsin a wearer's foot. Also, if desired, lines of flex may be provided inthe heel area in at least some example sole structures. Such designsallow the wearer to adjust more naturally to a particular terrain, wherefor example the lateral side may flex more than the medial side and viseversa. Such footwear allows more of the sole to remain in contact withthe ground providing a solid base for support for movement and activity.

Additional Elements

The footwear according to some examples of this invention may includeadditional features or structures. If desired, some portions of theshock absorbing cushion (60) and/or of the outsole (70) may be at leastpartially filled with another material, e.g., a material softer than amaterial making up a major portion of the shock absorbing cushion or theoutsole, to further promote the flexibility characteristics of theshoe's structure while preventing wearer feel of ground elements.

The footwear further may include plural ground penetrating tractionelements, commonly referred to as “traction lugs” (78), illustrated inFIG. 5. The shape of the traction lugs is determined by the positions ofthe various treads, or spaces that extend upward into the outsolematerial and extend between the sole elements forming an articulatedconfiguration of the bottom ground-facing surface of outsole. Forexample, the outsole (70) may include one or more traction lugs in itsforefoot or heel portions, extending in the lateral or longitudinaldirections on the bottom surface of the outsole. Preferably the tractionlugs will be placed at locations corresponding to natural footflexibility, to provide additional flexibility and lines of flex and tofurther improve traction capability in desired applications. Typicalembodiments of the invention will comprise outsoles having a “breasted”heel with lateral tread to render improved traction to the shoe, thusallowing full range of motion such as walking, running or climbing.Accordingly, tread marks are formed and distributed over the bottomsurface of the outsole to selectively vary the degree of stretch andflexibility in specific portions of the outsole. In addition tofunctionality, the traction lugs and tread marks are often applied tovary the overall aesthetics (e.g., color) of the outsole of the shoe asdesirable to consumers.

Additional traction elements, such as golf spikes, may be attached atvarious locations on the exterior surface of the outsole. These tractionelements may be mounted to the outsole member in any desired manner,including via threads, other retaining systems, etc., including throughthe use of conventional mounting systems that are known and used in theart. Any type or arrangement of traction elements may be used withoutdeparting from the invention. Such traction elements may be included aspart of the sole structure in any desired manner without departing fromthe invention, such as by integrally molding them into the solestructure along with other portions of the sole or by attaching them tothe sole structure (e.g., by adhesives, cements, screws, clasps,retaining elements, other mechanical connectors, etc.) If desired,according to at least some examples of this invention, traction elementsof the types and/or in the arrangements shown in U.S. Pat. Nos.6,817,117 and/or 6,705,027 may be used without departing from thisinvention, each of which is incorporated herein by reference.Additionally or alternatively, if desired, any indentations, weld areas,or other recessed structures on the exterior surfaces of the outsole mayinclude additional support structures, such as plastic supports (e.g.,PEBAX® (a polyether-block co-polyamide polymer available from AtofinaCorporation of Puteaux, France), which can help make the lateral sidemore stable and less flexible than the medial side. In addition, otherways of providing lateral support and/or medial flexibility may be used,in place of or in combination with the various examples described above,without departing from the invention. Also, if desired, various types ofheel units, midsole elements, or impact-attenuating elements orstructures may be provided without departing from the invention, such asconventional foam or other impact-attenuating materials, columnar shockabsorbing type elements and the like.

It is one advantage of the invention that if components of the sole (30)of the invention becomes worn or otherwise damaged, the damagedcomponent may be replaced without the necessity of replacing theundamaged component, and the damaged component may be more easilyrecycled. For example, since the outsole will be generally formed from apolymer material, following significant use, the polymer foam materialmay experience compression set or otherwise degrade or becomesignificantly worn. Rather than dispose of the footwear (10), either theshock absorbing cushion (60) or the outsole (70) may be properlyrecycled and replaced with an alternate component, respectively, thusextending the lifespan of the footwear. In the event that the lateralregion (80) of the outsole becomes punctured, only the lateral outsolecomponent can be replaced, without replacing the medial region (90) ofthe outsole and in lieu of replacing the entire outsole. Furthermore,the outsole may be interchanged with alternate components to suit aparticular activity or a preference of an individual.

Manufacturing

A number of manufacturing methods are suitable for forming the soleelements of the invention. Conventional footwear construction generallyfollows two methods, welted construction and molded construction. In theinvention herein, the outsole may be formed as a unitary element withthe central flex channel (72) subsequently formed through an incisionprocess, for example. The outsole may also be molded such that thecentral flex channel is formed during the molding process. Suitablemolding methods for the outsole, the shock absorbing cushion, and themidsole include injection molding, pouring, or compression molding, forexample. In each of the molding methods, a blown polymer resin is placedwithin a mold having the general shape and configuration of the desiredstructural element. The mold includes thin blades that correspond withthe positions of the flex channels. The polymer resin is placed withinthe mold and around each of the blades. Upon setting, the structuralelement is removed from the mold, with the desired dimensions beingformed during the molding process.

The central flex channel (62) of the invention may be provided in theoutsole (60) structure during the manufacturing process, such as duringa sole member molding process, by a cutting action (e.g., using knives,blades, lasers, etc.), and/or in any other manner, including inconventional methods known and used in the art for the manufacture ofoutsoles. Any desired types of materials may be used for the structuresof the shock absorbing cushion (60) and central flex element (62) andthe outsole (70) structures, including rubber or polymeric materials(such as thermoplastic polyurethanes), including materials that areknown and conventionally used in the art. As some more specificexamples, the outsole material may be constructed from a rubbermaterial, e.g., having a hardness of 60 to 90 Shore A (and in someexamples, 64-70 Shore A), and the shock absorbing cushion (60) materialmay have about the same level of hardness, or perhaps a bit softer(optionally made from rubber or a thermoplastic polyurethane material).The material of the shock absorbing cushion (60) and central flexelement (72) need not be the same material as the outsole (70), and canbe made of either a harder or a softer material. Of course, a widevariety of materials, hardness, combinations of materials, and/orcombinations of hardness may be used without departing from theinvention.

As discussed above, the sole (30) is permanently secured to the lowerportion of the upper (20). A variety of attachment techniques may beutilized for permanently securing the outsole to the sides of the upper,including stitching, adhesive bonding, thermobonding, or a combinationthereof, for example.

The various structural features and the various aspects of the inventiondescribed above may be used in any desired combinations, permutations,and sub-combinations without departing from the invention. It will beapparent to those skilled in the art that various modifications may bemade to the present invention without departing from the intended scopeof the invention since it is not considered limited to the specificembodiments described in the specification and drawings.

What is claimed is:
 1. An article of footwear having a forefoot region,a midfoot region, a heel region, a lateral region, a medial region, anupper structure and a sole structure, the sole structure comprising: amidsole positioned along the longitudinal length of the downward-facingsurface of the upper structure and connected thereto; and a shockabsorbing cushion integrally connected to the downward-facing surface ofthe midsole; and an outsole integrally connected to the downward-facingsurface of the shock absorbing cushion, said outsole comprising at leastone flex channel in the form of an aperture in the outsole; and whereinthe shock absorbing cushion extends downward and protrudes through andalong said flex channel of the outsole forming a corresponding flexelement.
 2. The article of footwear of claim 1, wherein the flex channelis oriented in a longitudinal direction of the footwear from theforefoot region to the heel region.
 3. The article of footwear of claim2, wherein the flex channel extends substantially centrally in thelongitudinally direction of the footwear.
 4. The article of footwear ofclaim 1, wherein the flex channel is oriented in a substantially lateraldirection of the footwear from the medial region to the lateral regionof the footwear.
 5. The article of footwear of claim 1, wherein thefootwear comprises a plurality of flex channels in the outsole withcorresponding flex elements.
 6. The article of footwear of claim 3,wherein the medial region and the lateral region are partially connectedto one another.
 7. The article of footwear of claim 6, wherein medialregion and the lateral region are connected to one another at the heelor at the toe or both.
 8. The article of footwear of claim 1, whereinthe outsole extends partially upward from the sole structure to theupper structure to form the welt of the footwear.
 9. The article offootwear of claim 1, wherein the thickness of the shock absorbingcushion varies along the forefoot region, the midfoot region, the heelregion, the medial region and/or the lateral region.
 10. The article offootwear of claim 1, wherein the width of the flex element isapproximately equal to the width of the flex channel.
 11. The article offootwear of claim 1, wherein the thickness of the flex element isapproximately equal to the thickness of the flex channel.
 12. Thearticle of footwear of claim 1, wherein the thickness of the shockabsorbing cushion is from about 4 to about 15 mm.
 13. The article offootwear of claim 1, wherein the thickness of the flex element is fromabout 8 to about 10 mm.
 14. The article of footwear of claim 1, whereinthe shock absorbing cushion comprises polyurethane or ethylvinylacetate.15. The article of footwear of claim 1, wherein the outsole furthercomprises traction lugs.